How to calculate maximum surface pressure a silicon wafer can withstand?

In summary: Heston: In summary, the equation you are struggling with is related to the stress intensity factor and fracture toughness of the material. You should speak to a professor at your university to get more information on the subject. You should also do some destructive testing to get a better idea of the variability of the material you are using.
  • #1
Katana750
3
0
Long story short, I'm working on a senior design project this semester, (involves converting a gassified biomass to a liquid ethanol using a palladium catalyst embedded in a silicon microporous matrix). I'm currently struggling what should be a fairly basic equation, but it's been too long since I've looked at such equations. Given known dimensions of the silicon wafer, (including the fact that we're removing 75% of the volume of the silicon due to the pores). The pores are small enough (3.5nm) that I assume we can generally assume the pressure relief offered by the pores is negligible.

Anyway, the question is, what equation gives us the maximum pressure the top surface of the volume can support without collapsing? (We will need to develop a pressure above the matrix to generate a reasonable flow rate through the pores).

Thanks in advance!
 
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  • #2
Katana750 said:
Long story short, I'm working on a senior design project this semester, (involves converting a gassified biomass to a liquid ethanol using a palladium catalyst embedded in a silicon microporous matrix). I'm currently struggling what should be a fairly basic equation,

It is not a basic equation..
See here:
http://en.wikipedia.org/wiki/Bending_of_plates

Add that to the fact your material is full of holes which act as many cracks so stress intensity factors are important:

http://en.wikipedia.org/wiki/Stress_intensity_factor

http://en.wikipedia.org/wiki/Fracture_toughness
Katana750 said:
The pores are small enough (3.5nm) that I assume we can generally assume the pressure relief offered by the pores is negligible.
The load will depend entirely on the pressure difference from one side to the other and that depends on the flow rate.

I'd suggest talking to the relevant professor at your university. Also, do some destructive testing to get some idea of the variability of your material and whether real results align with theoretical results
http://en.wikipedia.org/wiki/Destructive_testing
 
  • #3
You need to study up a little on the subject of Poroelasticity, which handles stress analysis in porous materials with internal pressurization. Look up Terzaghi Effective Stress.

Chet
 

1. How is the maximum surface pressure of a silicon wafer calculated?

The maximum surface pressure of a silicon wafer can be calculated by dividing the yield strength of the material by a safety factor. The yield strength is a measure of the maximum amount of stress that a material can withstand before permanent deformation occurs. The safety factor is typically chosen based on the level of risk and uncertainty in the calculation.

2. What factors affect the maximum surface pressure a silicon wafer can withstand?

The maximum surface pressure a silicon wafer can withstand can be affected by various factors such as the thickness of the wafer, the size and shape of the wafer, the properties of the material, and the surface condition of the wafer. Other external factors such as temperature, humidity, and mechanical stress can also influence the maximum surface pressure.

3. Can the maximum surface pressure of a silicon wafer be increased?

Yes, the maximum surface pressure of a silicon wafer can be increased by using a thicker wafer, improving the quality of the material, or using a different material with a higher yield strength. However, it is important to carefully consider the potential risks and limitations before increasing the maximum surface pressure.

4. How important is accurate measurement in calculating the maximum surface pressure of a silicon wafer?

Accurate measurement is crucial in calculating the maximum surface pressure of a silicon wafer. Any errors or uncertainties in the measurement can significantly affect the accuracy of the calculation and potentially lead to failure of the wafer. It is important to use precise and calibrated equipment for measurement and to follow standard measurement procedures.

5. What is the typical maximum surface pressure that silicon wafers can withstand?

The maximum surface pressure that silicon wafers can withstand varies depending on the size, thickness, and properties of the wafer. Generally, silicon wafers can withstand a maximum surface pressure of around 1 GPa (145,000 psi) before failure occurs. However, this value can differ significantly depending on the specific conditions and factors involved.

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